I've done it a few times. It is a fun thing to do.
The easiest way to do it is with a pair of GPS'es. I use a Garmin streetpilot III to find the public road nearest the cache, as well as alternate accesses. The SPIII has road maps AND routing, so it can help you find your way to the cache too.
I use a small garmin e-map when doing the walking part. It's remarkably accurate and will get you within 15 feet or so of the cache.
A topo map is helpful when you are off road. It lets you decide not to take a direct route that includes a steep hill.
I'm not a hiker, so it it's more than 1/2 mile from the nearest road, I won't do it. I will also avoid cow pastures in the future.
Daniel